The Valve,check, cataloged under National Stock Number 4820-01-059-1173, is classified within Federal Supply Class 4820 (Valves, Nonpowered) of the Valves group. The manufacturer of record is Lourdes Industries, Inc.. Government technical data includes 30 specifications, cited from the U.S. Government catalog. The record lists 2 manufacturer part numbers for this item, enabling identification through both NSN and commercial part number lookups. 1 additional reference document (drawings, advisory and superseded references) is recorded in the U.S. Government catalog. 2 items share a part number with this NSN in the catalog (possible match — not a government interchangeability claim). Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 4820-01-059-1173 |
| Primary Part Number | L81400-20FMK |
| Item Name | Valve,check |
| FSC / FSG | 4820 / 48 — Valves, Nonpowered |
| Manufacturer | Lourdes Industries, Inc. |
| Status | ACTIVE |
| Flow Control Device | POPPET |
| Flange Shape | RECTANGULAR WITH HOLES SECOND END |
| Flange Face Design | PLAIN SECOND END |
| Surface Treatment Document and Classification | MIL-A-8625 MIL SPEC SINGLE TREATMENT RESPONSE |
| Connection Style | PLAIN (TUBE) FIRST END |
| Nominal Length | 2.188 INCHES SECOND END IN |
| Mounting Position | HORIZONTAL |
| Connection Type | FLANGE SECOND END |
| Connection Type | UNTHREADED EXTERNAL TUBE FIRST END |
| Style Designator | STRAIGHT THRU |
| Material Document and Classification | MIL-R-25897, TYPE 1, CLASS 1 MIL SPEC SINGLE MATERIAL RESPONSE SEAT |
| Material Document and Classification | QQ-A-200/3, ALLOY 2024, T4 FED SPEC SINGLE MATERIAL RESPONSE FLOW CONTROL DEVICE |
| Material Document and Classification | QQ-A-225/8, ALLOY 6061, T651 FED SPEC SINGLE MATERIAL RESPONSE BODY |
| Bolt Hole Nominal Diameter | 2.500 INCHES SECOND END IN |
| Nominal Outside Diameter Tube Accommodated | 1.520 INCHES FIRST END IN |
| Operating Pressure | 400.0 POUNDS PER SQUARE INCH (PSI) MAXIMUM SINGLE RESPONSE LBS |
| Maximum Operating Temp | 400.0 FAHRENHEIT SINGLE RESPONSE DEGF |
| Center to Center Nominal Distance Between Bolt Holes Along Width | 1.656 INCHES FIRST END IN |
| Disk Loading Method | SPRING |
| Bolt Hole Quantity | 4 SECOND END |
| Surface Treatment | ANODIZE |
| Nominal Width | 2.188 INCHES SECOND END IN |
| Center to Center Nominal Distance Between Bolt Holes Along Length | 1.656 INCHES SECOND END IN |
| Media for Which Designed | FUEL/OIL, HYDROCARBON SECOND RESPONSE |
| Media for Which Designed | AIR FIRST RESPONSE |
| Material | ALUMINUM ALLOY 2024 FLOW CONTROL DEVICE |
| Material | ALUMINUM ALLOY 6061 BODY |
| Material | RUBBER SEAT |
| Valve Operation Method | AUTOMATIC |
| Nominal Thickness | 0.300 INCHES SECOND END IN |
| Acquisition Status | ACTIVE |
| DEMIL Code | DEMIL A — No Demilitarization Required |
| Hazard | No hazard code in the DLA record (HMIC N) |
| Criticality Code | X |
| Part Number | Manufacturer |
|---|---|
| GV500TC20FMK | Northrop Grumman Systems Corporation (USA) |
| L81400-20FMK PRIMARY | Lourdes Industries, Inc. (USA) |
| Reference | Meaning |
|---|---|
| GV500TC | D/9 Drawing number reference only Northrop Grumman Systems Corporation |
NSN 4820-01-059-1173 is a Valve,check, manufactured by Lourdes Industries, Inc., classified under FSC 4820, Valves, Nonpowered. Status: active.
NSN 4820-01-059-1173 has 2 manufacturer part numbers on file: GV500TC20FMK (Northrop Grumman Systems Corporation), L81400-20FMK (Lourdes Industries, Inc.).
2 possible matches (shared part number, not a government interchangeability claim): 4820-01-259-0347, 4820-01-259-2204. Verify interchangeability with system specifications before substitution.
Key specifications for L81400-20FMK: Flow Control Device: POPPET; Flange Shape: RECTANGULAR WITH HOLES SECOND END; Flange Face Design: PLAIN SECOND END; Surface Treatment Document and Classification: MIL-A-8625 MIL SPEC SINGLE TREATMENT RESPONSE. 30 specifications are documented in the U.S. Government catalog.
No hazard code in the DLA record (HMIC N). Hazard information on this page is shown exactly as it appears in the DLA record.
U.S. Government catalog: edition PUBLOGDVD v12.0.0 (OCT 2026), edition date 2026-10-01, retrieved 2026-10-16.
U.S. Government catalog: edition PUBLOGDVD v12.0.0 (OCT 2026), edition date 2026-10-01, retrieved 2026-10-18.